Chicago Fire Team Faces 'Outside Threats' to Its Survival -- Plus: Which Friendships Are in Peril?

In an emergency, there’s no time to waste. So NBC’s rescue drama Chicago Fire is jumping right back into the fiery action when Season 2 premieres Tuesday at 10/9c.

“We’re starting off with a bang,” says executive producer Derek Haas. “We’re throwing everything at the audience. There are four or five storylines going on, a lot of conflict. There’s an outside threat to the firehouse – more than one, actually. One is physical, and one is mental.”

On top of that danger, there’s a baby issue, several romances, some new enemies and a few tested friendships. Read on for all the scoop.

TOTS AND PALS | Yes, Sarah Shahi – who’s now a series regular on time-slot competitor Person of Interest – will return for an episode to wrap up the Renée/Severide storyline and to throw “a big wrench” in her guy’s baby plans with buddy Shay, previews EP Danielle Gelber. “It’s obviously going to… create a lot of trust issues. Ultimately, you’re going to find that it stretches Shay and Severide’s relationship to the edge, and then like a rubber band, you’ll see them come back together.” With everything that is going on between himself, his pregnant ex and his BFF, the firefighter’s “head is in a lot of different places at once, because he is quite understandably, emotionally, pulled into two different directions.” Warns EP Michael Brandt: “That storyline is going to stay fraught for a few more episodes, at least.”

ROMANCE REPORT | Dawson and Mills are split when the season starts; they will eventually see other people. Still, star Monica Raymund says, “We’re going to see a little bit of the Millson love come back in terms of how they navigate their relationship in Season 2.” Adds her co-star Charlie Barnett: “We brush up against each other a couple times.” Meanwhile, as we previously teased, emotional and romantic sparks will fly at some point between Dawson and Casey.

A BROKEN FRIENDSHIP | Uh-oh, there’s trouble ahead for besties Shay and Dawson! “This rift that you’ll see in Season 2, it does drive them apart for a while,” reveals Raymund. While it’s not the only disagreement the two have had, “It certainly is probably the biggest fight we’ve gotten in so far, I would imagine. [It] is going to have enough of an effect to affect our work and our relationship at the house. But I think Shay and Gabby are soulmates in terms of friends.”

THE NEW BOSS | Michelle Forbes (The Killing) joins the cast as a municipal consultant who immediately gains the firefighters’ ire thanks to her cost-saving implementations. “She comes in over Boden, and [due to] financial cutbacks in the department, Firehouse 51 — among others — is threatened for closure,” previews Gelber. “You see how that could potentially impact our guys. She will be a real thorn in their sides. But Boden, being the strong, stalwart chief, will try and take most of the heat and pressure on himself and let his guys do what they do best.”

DRINK UP | Molly’s will become more of a setpiece for the show in Season 2 when the establishment is threatened by a much bigger bar down the street. “We’re going to play that out over a while… what poor Molly’s has to do now to compete with a place that’s got 400 screens going on,” teases Brandt. Adds Haas: “They’re going to have to fight to keep it.”